It is very difficult to simulate nonlinear characteristics of concrete materials during fracturing process with continuum mechanics models. Discrete element methods supply for a new way for solving this kind of problems. However, how to precisely determine parameters of micro-constitutive model of concrete materials has become a key problem that affects the development and practical application of discrete element methods. The nonlinear mapping relation between deformation data of concrete specimen and parameters of micro-constitutive model of concrete materials is bridged by response surface function. Based on macro experimental data and response surface function, parameters of micro-constitutive model of concrete materials are determined by using optimization algorithm. The investigation result validates that the forecasted stress-strain curve for concrete specimen agrees well with observed one. The parameter inversion of micro-constitutive model for concrete materials can supply for foundations for precisely numerical simulation of discrete element methods.